I run QET on Plasma.
I normally have nine (3x3) desktops i can quickly switch between for different tasks.
I normally want program toolbars detached and placed at very top of screen, (most program top frame right part is just uninteresting grey area so let us use it!) which means i get larger drawing area.
Problem: QET floating toolbars shows up on all desktops; also on top of other programs.
Workaround: I minimise QET before switching desktop.
( but that need one extra mouse click, oh, my...! Other programs do not need be minimised for their toolbars not to show up on other desktops )
Anyway it is not looking polished and i was thinking maybe some developer know a quick fix to apply in QET, or for now maybe a setting user can do somewhere in Plasma?